Typically, in an inductive power transfer system, the primary inductor of the inductive power transmitter is in the shape of a coil. However a coil-shaped primary inductor is not optimal for creating a large charging surface. An inductive power transmitter with the primary inductor being a large-diameter coil has a flaw that the resulting magnetic field lacks uniformity and can vary in intensity over several orders of magnitude. The induced voltage generated in a small-diameter secondary inductor, when placed in the center region of the large-diameter primary inductor (weak magnetic field) compared to when placed near the edge of the same primary inductor, can potentially vary from 1 to 100 volts (depending of the specifications of the system). Further, the non-uniformity of the magnetic field becomes worse as the diameter of the primary inductor coil is increased. In addition, the extension of the magnetic field in the Z axis increases with the diameter of a coil-shaped primary inductor, which may or may not be desired.
Thus, an improved inductive power transfer system with an inductive power transmitter capable of transmitting power to an inductive power receiver with more uniformity across a wide area is desired.